NASA Finds Cause of Voyager 2 Glitch 283
astroengine writes "Earlier this month, engineers suspended Voyager 2's science measurements because of an unexpected problem in its communications stream. A glitch in the flight data system, which formats information for radioing to Earth, was believed to be the problem. Now NASA has found the cause of the issue: it was a single memory bit that had erroneously flipped from a 0 to a 1. The cause of the error is yet to be understood, but NASA plans to reset Voyager's memory tomorrow, clearing the error."
Cosmic Ruse (Score:2, Interesting)
First I was going to suggest that this satellite would careen forward out of control like a Toyota, but then realized that wouldn't be quite accurate.
The cosmic rays we get one Earth are actually short-lived particles such as muons (a fat electron, probably most well known aside from the standard protons-neutrons-electrons) that result from cosmic naked hydrogens hitting our atmosphere. Out in space though, it'd be interesting to see if those protons would have the same effect as a terrestrial "cosmic ray".
Re:Hero (Score:1, Interesting)
Emergency room doctors are mechanics, not scientists.
They're paid to fix people, not find truth.
Re:Really? (Score:4, Interesting)
Certainty? I don't think so.
I think they simulated Voyager with this bit flipped and saw the same output (that is transmitted to earth).
I hope they tried to flip ALL bits, and found that only this one bit would give the results seen. If you would follow the code and find and test just a few likely places, I'd expect a few more unexpected places to give the same results.
The quick fix is to send the correct byte to the craft and hope that fixes it. If the bit has become stuck in the new position, they will have to do a remote firmware upgrade (with the code rewritten to fit the stuck-at value...) Other memory cells may have broken down in the mean time, but with a stuck-at value that is correct for the current version of the firmware, which you won't know until you try them....
Re:Really? (Score:3, Interesting)
You're the second one to suggest "age". When humans die of age, that's some failure in the human body that's common when people grow old. That's when we say someone died of old age. However when human made devices die, there is always a component that has failed. When you have a 5 year old mobile telephone that dies, you say it died of old age, and replace it. That's because you don't care and replacing it costs less than finding out the root cause for the failure.
When a properly designed computer flips a bit, SOMETHING happened. We may never know, it might have been a cosmic ray. But don't you think that they would use space-certified RAM chips for such a project?
In any case, I don't know what memory technology voyager uses. The (slightly) more modern space shuttles used magnetic core memory for essential systems. These are not affected by cosmic rays. If it isn't magnetic core, then it is likely to be static RAM. This too is not easily modified by a cosmic ray. Modern DRAM however is easily affected by cosmic rays. But exactly because of that, it's not likely that they used DRAM.
In 1977, when the voyagers were launched, DRAM had been commercially available for 7 years.... This might have been too new for NASA to design into their new babies....
Cosmic ray examples (Score:3, Interesting)
While not naming specifically cosmic rays as the cause in this case, what examples of actual cosmic ray-induced debacles are there in software eng. history?
Re:Just incredible! (Score:5, Interesting)
>>>have their infinitely "more powerful" laptop process 5% of the NYSE volume like our mainframes did, while supporting about 100K trader desks, a couple TB of tape robot storage, etc.
A laptop could do that if it had an efficient assembly-written OS (like Kolibri), rather than the bloated general purpose OSes like Windows NT or OS X. At my former company we used the equivalent of laptops (Pentium 2s) to manage, load mission data, and launch a ship full of Tomahawk missiles.